Cushion for a Patient Interface

ABSTRACT

A respiratory mask is provided having an outer shell coupled to a cushion for the delivery of a gas to a user. The cushion of the respiratory mask has a pleat and varied wall thicknesses about the device in order to provide varying degrees of flexibility and support about the cushion.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a Continuation and claims priority under 35 U.S.C. §120 from U.S. patent application Ser. No. 11/312,026 filed Dec. 20, 2005which claims priority under 35 U.S.C. § 119(e) from provisional U.S.Patent Application No. 60/638,869 filed Dec. 22, 2004 the contents ofeach of which are incorporated herein by reference.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention pertains to a respiratory patient interface usedto deliver gas to a user. In particular, the present invention isrelated to a respiratory patient interface having a cushion with apleat.

2. Description of the Related Art

Obstructive sleep apnea or OSA, obstructive sleep hypopnea, and upperairway resistance syndrome (UARS) are among a variety of known disorderscharacterized by episodes of complete or partial upper airwayobstruction during a state of diminished consciousness, such as sleep,anesthetization, or post anesthesia. OSA, hypopnea, and UARS causeintermittent interruption of ventilation during sleep with theconsequence of potentially severe oxyhemoglobin desaturation. Typically,those afflicted with OSA, hypopnea, and UARS experience repeated,frequent arousal from sleep in response to the oxygen deprivation. Thearousals result in sleep fragmentation and poor sleep continuity.

Consequences of OSA, hypopnea, and UARS may include debilitating daytimesleepiness and cognitive dysfunction, systemic hypertension, cardiacdysrythmias, pulmonary artery hypertension and congestive heart failure.Other consequences may include a predisposition to myocardialinfarction, angina pectoris, stroke, right ventricular dysfunction withcor pulmonale, carbon dioxide retention during wakefulness as well asduring sleep, and continuous, reduced arterial oxygen tension. Moreover,the cognitive impairment resulting from OSA, hypopnea, and UARS putsthose afflicted at elevated risk of accidents.

The pathogenesis of the airway obstruction that characterizes OSA,hypopnea, and UARS can include both anatomic and functionalabnormalities of the upper airway that result in increased air flowresistance. Such abnormalities may include narrowing of the upper airwaydue to suction forces created during inspiration, the effect of gravitypulling the tongue back to appose the pharyngeal wall, and insufficientmuscle tone in the upper airway dilator muscles, among others. It isalso believed that excessive soft tissue in the anterior and lateralneck, as commonly observed in obese persons, can apply sufficientpressure to internal structures to narrow the upper airway and restrictair flow.

Conventional treatment of OSA, hypopnea, and UARS has included surgicalintervention, such as uvalopalotopharyngoplasty, gastric surgery forobesity, mandibular advancement procedures, maxillo-facialreconstruction, and tracheostomy. However, surgery potentially involvesconsiderable risk of post-operative morbidity and mortality. Inaddition, the failure rate of surgery is disturbingly high.Pharmacological therapy has also been proposed to treat OSA, hypopnea,and UARS; however, results have been generally disappointing.

More recently, continuous positive airway pressure (CPAP) or bi-levelpositive airway pressure applied during sleep has been used to treatOSA, hypopnea, and UARS patients. Positive pressure is applied in theupper airway to splint or support the airway open, thereby preventingits collapse and the resultant airway obstruction. A typical positiveairway pressure device comprises a flow generator (e.g., a blower) thatdelivers gas via a delivery conduit to a patient interface, such as amask. It is also known to deliver the positive airway pressure therapyas a continuous positive airway pressure (CPAP), a variable airwaypressure, such as a bi-level pressure that varies with the patient'srespiratory cycle (Bi-PAP), or an auto-titrating pressure that varieswith the monitored condition of the patient. Pressure support therapiesare also provided to treat other medical and respiratory disorders, suchas Cheynes-Stokes respiration, congestive heart failure, and stroke.

Many patient interfaces are well known in the art. For instance, maskswhich provide a seal between the compressed air and the patient arecommon. These interfaces include nasal pillows with prongs which fitinto the nares of the patient, nasal masks which fit over the patient'snose, nasal-oral masks that fit over the mouth and nose, and full facemasks which fit over the patient's entire face. For such devices to beeffective, two competing goals need to be balanced: comfort and support.Comfort may be enhanced by reducing the area of contact between the maskand the patient; or use of a soft, lightweight, flexible material. Ifthe mask proves to be uncomfortable, patient compliance will be low. Incontrast, to enhance the ability of the mask to support its weight andassociated hoses and attachments, the mask should ideally be constructedfrom a rigid material and have a large contact area between the mask andthe patient.

One mask which attempts to balance the competing goals of comfort andsupport is disclosed in U.S. Pat. No. 4,907,584. This mask has a rigidsupport portion and a cushion. The cushion includes a flexible flap toform a seal between the patient and the mask. In order for the flap tooperate effectively, the flap must be sufficiently rigid to support themask and sufficiently flexible to be comfortable. Although the '584patent has substantially advanced the art, it could still be furtherimproved upon. For instance, since the flap is required to balancebetween comfort and support, the resulting design must compromisebetween these two goals.

Other patient interfaces have been suggested which have separatestructural features to address the competing goals of support andcomfort. For instance, U.S. Patent Application Publication No.2004/0112385 discloses a mask having a rigid support attached to acushion. The cushion disclosed in the application includes a doubleflap. The outer flap contacts the face of the patient and is formed tobe flexible in order to provide a comfortable seal. The inner flap isformed to provide support to the cushion either alone or in combinationwith the outer flap.

This device advances the art by separating the two competing goals ofcomfort and support into separate structural elements. By so doing, thisallows each of these features to be customized to achieve their separatepurpose rather than having a single structural element which attempts tobalance these two competing goals. Yet, even this design presentsseveral drawbacks. One major drawback to this design is that it assumesthe forces exerted on the mask are consistent about its circumference.In reality, the region about a patient's mouth and/or nose has a complexgeometry requiring differing amounts of flexibility and support toachieve an adequate seal and differing amounts of rigidity to provideadequate support. Secondly, forming a cushion with an internal flap hasproved difficult to manufacture and has resulted in rejects and wastedmaterial. Typically, these masks are manufactured by an injectionmolding process. One drawback to this manufacturing method is that it isdifficult to flow material into thin walls and undercuts as is needed toform this type of cushion.

To overcome these disadvantages, other masks have been suggested toprovide a separate structure to seal the mask and a separate structureto provide support while simplifying the manufacturing process. One suchmask is disclosed in U.S. Pat. No. 5,349,949. The mask disclosed in thispatent has a rigid shell provided with fastening straps to hold the maskon the user's head. Connected to the shell is a face cover constructedfrom an elastomeric material. The face cover contacts the user's facealong an internal lip. Adjacent to the lip is a deformable fold withresilient spring-like elements. One advantage this device has over thedevice disclosed in the previous publication is that it removes the thinwalls and undercuts while separating the structure used to provide aseal from the structure used to provide support to the face cover. Yet,even this device has several drawbacks. For instance, the deformablefold has a consistence shape about the circumference of the face cover.Therefore, it is incapable of providing differing support andflexibility as needed about the user's face.

Accordingly, it would be desirable to have a respiratory mask that isconfigured to deliver a gas to a patient. It would also be desirable tohave a respiratory mask that provides separate structural elements toprovide support and flexibility to the respiratory mask. It would befurther desirable to have a respiratory mask which is capable ofproviding differing support and flexibility in different regions of themask. It would still be further desirable to have a respiratory maskthat is capable of providing the above noted features while beingconstructed in a manner that simplifies the manufacturing process.

SUMMARY OF THE INVENTION

In accordance with the broad teachings of the invention, a cushion for arespiratory mask having a shell and a cushion is disclosed. The cushionincludes three portions: a flap portion, a middle portion, and aconnection portion. The connection portion is adapted to couple with theshell of the respiratory mask. The middle portion provides moderatesupport and flexibility. The flap portion is configured to provide acomfortable seal with the user's face by providing more flexibility. Thecushion further includes a pleat about a portion of the cushion toprovide a localized region of flexibility for forces exerted in an axialdirection toward or away from the user's face. The pleat also providessome additional rigidity for forces which are exerted in a directionother than axially.

In another aspect, the invention includes a cushion for a respiratorymask having a coupling and a nasal pillow. The nasal pillow includes ahollow body in communication with at least one nare element. The nareelement has an opening to permit fluid communication between a patientand the coupling via the hollow body. The nare element further includesa pleat about a portion of the nare element to provide a region oflocalized flexibility.

These and other objects, features, and characteristics of the presentinvention, as well as the methods of operation and functions of therelated elements of structure and the combination of parts and economiesof manufacture, will become more apparent upon consideration of thefollowing description and the appended claims with reference to theaccompanying drawings, all of which form a part of this specification,wherein like reference numerals designate corresponding parts in thevarious figures. It is to be expressly understood, however, that thedrawings are for the purpose of illustration and description only andare not intended as a definition of the limits of the invention. As usedin the specification and in the claims, the singular form of “a”, “an”,and “the” include plural referents unless the context clearly dictatesotherwise.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a side elevational view of the respiratory mask of the presentinvention;

FIG. 2 is a bottom plan view of the respiratory mask and a schismatic ofa conduit and a positive airway pressure device;

FIG. 3A is a front elevational view of a cushion of the respiratorymask;

FIG. 3B is a side elevational view of the cushion;

FIG. 4A is a top plan view of the cushion;

FIG. 4B is a bottom plan view of the cushion;

FIG. 5 is a side cross-sectional view of the cushion along line 5-5 ofFIG. 3;

FIG. 6 is a cross-sectional view of the cushion along line 6-6 of FIG.3;

FIG. 7 is a cross-sectional view of the cushion along line 7-7 of FIG.3;

FIG. 8 is a cross-sectional view of the cushion along line 8-8 of FIG.3;

FIG. 9 is a cross-sectional view of the cushion along line 9-9 of FIG.3;

FIG. 10A is a top perspective view of an alternative embodiment of thecushion;

FIG. 10B is a bottom perspective view of a first alternative embodimentof the cushion;

FIG. 11 is a side elevational view of a first alternative embodiment ofthe cushion;

FIG. 12 is a front perspective view of a second alternative embodimentof the cushion;

FIG. 13 is a rear perspective view of the second alternative embodimentof the cushion;

FIG. 14 is a side elevational view of the second alternative embodimentof the cushion;

FIG. 15 is a front elevational view of the second alternative embodimentof the cushion;

FIG. 16 is a top plan view of the second alternative embodiment of thecushion;

FIG. 17 is a rear perspective view of a coupling of the secondalternative embodiment of the cushion;

FIG. 18 is a bottom perspective view of a deformable support of thesecond alternative embodiment of the cushion; and

FIG. 19 is a cross-sectional view of the nasal cushion of the secondalternative embodiment along line 19-19 of FIG. 16.

DETAILED DESCRIPTION OF THE PRESENTLY PREFERRED EMBODIMENTS OF THEINVENTION

FIG. 1 schematically illustrates an exemplary embodiment of a patientinterface 30 having a cushion 32 attached to a shell 34 by a capturering 33. The capture ring fits about cushion 32 and connects to shell 34to capture a portion of cushion 32 between capture ring 33 and shell 34.Cushion 32 may be attached to shell 34 in a variety of other methodsknown in the art. For instance, the cushion could be attached via anadhesive to the shell. Alternatively, the cushion could be attached byovermolding the cushion onto the shell. Of course, other methods ofinterconnecting the shell to the cushion may be contemplated withoutdeparting from the scope of the present invention.

The patient interface also includes a forehead support 36 and a coupling38 connected to the shell 34. A conduit 35 is connected to the patientinterface 30 via coupling 38. The conduit delivers pressurized gasproduced by a positive pressure device 37 to the patient interface. Thepositive pressure device may create pressurized gas in any of a numberof commonly known methods such as continuous positive pressure, variablepressure (such as a bi-level pressure that varies with the patient'srespiratory cycle), or an auto-titrating pressure that varies with themonitored condition of the patient.

As seen in FIG. 1, forehead support 36 has a frame 40 that extends awayfrom shell 34. The frame is attached to the shell at one end andsupports a pad 42 at the other end. Between pad 42 and frame 40 there isa rigid base 44. The respiratory mask is held in place on a user's faceby headgear, not shown. The headgear is connected to the foreheadsupport by ears 46 extending from base 44. Similarly, shell 34 has slots48 adapted to receive pivot members, not shown, which are connected tothe headgear. Together, ears 46 and slots 48 secure the headgear to therespiratory mask. The pad is flexible so that it can conform to theparticular shape of the user's forehead.

As seen in FIG. 2, coupling 38 is an elbow connector 50 that is directedsubstantially coplanar with shell 34 so that the attached conduit doesnot extend directly perpendicular from shell 34. One of ordinary skillin the art can best appreciate that having a conduit which extendsperpendicularly from the respiratory mask would place increased pressureon the mask resulting in discomfort. In addition, having a conduitextending outward from the patient interface in this fashion may alsoprove to be unwieldy. Elbow connector 50 is pivotably connected to shell34 so that as the user moves about the conduit may also freely move.Otherwise, as the user moves, the conduit could exert forces on thepatient interface which could result in discomfort to the user or evencompromise the seal created between cushion 32 and the user's face.

As seen in FIGS. 3A, 3B, 4A, and 4B, cushion 32 has a generallytriangular-shaped periphery and fits over the user's nose. However, itis well known in the art that various patient interfaces can beconstructed which cover the user's nose and mouth (nasal-oral), cover amajority of the user's face (full-face mask), or fit within the user'snares. The present invention contemplates that the unique aspects ofthis invention could be utilized on a variety of different patientinterfaces without departing from the scope of this invention. Cushion32 is configured to provide a flexible seal between the user and theshell. In order to be effective, cushion 32 should be comfortable.Otherwise patient compliance would be reduced. In addition, cushion 32should also provide a substantially hermetic seal between the user andthe shell. The effectiveness of the cushion and the entire respiratorymask would be compromised if this seal is not maintained.

Cushion 32 has a flap portion 52, a middle portion 54, and a connectionportion 56. Each portion is specifically configured to achieve differentgoals. Flap portion 52 is configured to provide a secure seal betweenthe user and the shell. The middle portion is configured to providesupport to the cushion to resist the forces exerted upon the cushion.The connection portion is designed to provide a secure connectionbetween the cushion and the shell.

Each portion of the cushion has an apex region, a pair of side regions,and a bottom region. For instance, the flap portion has an apex flap 58adjacent a pair of side flaps 60. The side flaps are joined by bottomflap 62 to form a substantially triangular-shaped flap portion. Themiddle portion is adjacent to the flap portion. Middle portion 54 has amiddle apex region 64 adjacent a pair of middle side regions 66. Themiddle side regions are joined together by a middle bottom region 68.Lastly, the connection portion has an apex connection region 70 adjacenta pair of connection side regions 72. The side regions 72 are adjacentconnection bottom region 74. Connection portion 56 has a collar 76 whichmay be captured between shell 34 and capture ring 33 to form asubstantially hermetic seal with shell 34. Extending from collar 76 is apair of alignment projections 78 and alignment slots 80. Togetheralignment projections 78 and alignment slots 80 act to prevent cushion32 from being misaligned relative to shell 34.

Another aspect of this exemplary embodiment of the present invention isthe incorporation of a pleat 82 as best appreciated with reference toFIGS. 3B and 4B. The pleat extends about a portion of the cushion. Thepleat provides an integral corrugation which provides a spring-typeaction perpendicular to the pleat as indicated by double arrow A. Incombination with the varied wall thickness, this feature allows thespring to become progressively stiffer as it is compressed. This isaccomplished at least in part by having the pleat located adjacent theflap and extending inwardly. As pressure is applied to the flap, it willultimately abut against the pleat and become more rigid. In the eventthat multiple pleats are used, this feature can provide progressivelyincreasing resistance as the pressure is increased. Therefore, at theoption of the user, the amount of resistance provided by cushion may bevaried.

The use of pleats also simultaneously makes the cushion more rigid inthe off-axis direction indicated by double arrow B. This allows thecushion to resist radial forces applied parallel to the pleat. The depthof pleat 82 may be deepened to provide a more elastic region or thenumber of pleats could be increased to further enhance these effects. Inother regions, pleat 82 may be comparatively shallow or completelyremoved from some regions to reduce this effect.

Pleat 82 has a bottom pleat 84 which extends around the mid bottomregion 68 and a pair of side pleats 86 which extend up the mid sideregions 66. Finally, pleat 82 turns towards the connection portion 56and terminates with a pair of apex pleats 88. Apex pleats 88 are notinterconnected. Instead, apex pleats 88 terminate short of each other.Pleat 82 extends about the cushion proximate the flap portion whichallows the pleat to be more responsive to forces exerted in this regionof the cushion. Namely, pleat 82 is more responsive to forces exerted onthe flap by the user's face in direction B than by forces exertedradially inwardly on cushion in the direction indicated by arrow B.Alternatively, the pleat could be located in other regions of thecushion to be more responsive to the forces exerted in these otherregions of the cushion.

One of ordinary skill in the art can best appreciate that pleat 82 mayvary in the distance that it deviates. The pleat is shown extendinginwardly; however, the pleat could also extend radially outwardlywithout departing from the teachings of the present invention. However,it is presently contemplated that having the pleat extend inwardly ispreferable so that the overall size of the cushion is reduced. Moreover,having the pleat extend inwardly minimizes the possibility that externalitems could be pinched within the pleat. The height of the pleat mayalso be varied to adjust the strength provided by the pleat.

As shown in the exemplary embodiment, the pleat has a generally smoothlycurved configuration. However, the term “pleat” as used herein should bebroadly interpreted to include any feature which deviates from asubstantially planar region surrounding the pleat. For instance, thepresent invention also contemplates that the pleat may have a variety ofcross-sectional configurations including a smoothly curved cross-sectionor creased into a jagged saw-tooth or rectangular cross-section. Asshown in the first exemplary embodiment, the pleat is shown as a singlepleat. However, the present invention also contemplates that multiplepleats may be placed adjacent to one another to multiply the advantagesprovided by the pleat.

As seen in FIGS. 5 and 8, the apex flap, side flaps, and bottom flaphave lengths which vary between each region. Looking at thecross-section, it can be best appreciated that the flaps extend awayfrom the middle portion in a cantilevered manner. By altering the lengthof the flaps, the moment of inertia can be varied in different regions.For example, apex flap 58 may have a comparatively long length comparedto bottom flap 62 with side flaps 60 having a length which transitionsbetween the two. Providing apex flap 58 with a longer length permitsthis flap to be comparatively more deformable so that it can properlyseal against the rapidly changing geometry about the bridge of theuser's nose. In contrast, bottom flap 62 is comparatively shorter. Inthis region of the user's face, the geometry of the user's face changesvery slowly. Therefore, it is not necessary to have as deformable a flapas is needed in the apex region. Instead more support is needed in thisregion. Therefore, a flap with a shorter length is utilized.

With reference to FIGS. 6-9, the cross-sectional thickness of flapportion 52, middle portion 54, and connection portion 56 may be seen.Generally, the wall thickness of each portion varies with the connectionportion 56 being relatively thick. The middle portion has a generallymoderate wall thickness, and the flap portion has a relatively thin wallthickness. The wall thickness of connection portion 56 is relative thickin order to provide a secure interface with shell 34. The middle portionhas a moderate wall thickness in order to provide adequate strengthwithout wasting material. Finally, flap region has a comparatively thickwall thickness so that it may easily conform to the particular shape ofthe user's face. Otherwise, cushion 32 may not properly fit and resultin discomfort or poor sealing. Of course, one skilled in the art canbest appreciate that the wall thickness of these regions could be variedwithout departing from the teachings of the present invention.

In a second exemplary embodiment of the present invention, cushion 232is shown in FIGS. 10A and 10B as a nasal mask covering the user's nose.Once again, cushion 232 has a flap portion 252, a middle portion 254,and a connection portion 256. Cushion 232 has a first pleat 290 thatextends about a portion of the cushion and a second pleat 292 whichextends about another portion of the cushion. First pleat 290 includes abottom pleat 284, a pair of side pleats 286, and a pair of apex pleats288.

Similarly, the second pleat 292 has an apex pleat 294 and a pair of sidepleats 296. Second pleat 292 is shallower than first pleat 290.Accordingly, second pleat 292 is substantially more rigid than firstpleat 290 and thus more capable of resisting axially directed forcesthan first pleat 290. However, second pleat 292 is less rigid in theaxial direction than if this region did not have a pleat at all.

The first pleat extends about middle portion 254 and proximate flapportion 252. One can appreciate that the strength modifications thispleat provides will be more responsive to forces exerted on theconnection portion than forces exerted on the flap portion. In contrast,the second pleat extends about middle portion 254 and proximateconnection portion 256. The second pleat will be more responsive toforces exerted on the connection portion than the flap portion. Togetherthe first pleat 290 and second pleat 292 exhibit one embodiment of thepresent invention utilizing the unique strength modifyingcharacteristics of present invention. The first pleat is more responsiveto forces applied to flap portion 252 and provides a region on increasedflexibility about the mid bottom region and the mid side regions of flapportion 252. This creates a hinging motion relative to the mid apexregion of the cushion proximate flap portion 252. The second pleat ismore responsive to forces exerted on connection portion 256 and providesa region of increased flexibility about the mid top region and mid sideregions of the connection portion. This creates a hinging motionrelative to the mid bottom region of the cushion proximate theconnecting portion.

The connection portion of this exemplary embodiment also includes analignment projection 278. Unlike the prior embodiment, connectionportion 256 is formed having a shoulder 298 about step 200. However, theunique features of this invention can be utilized in a variety of maskswith differing connection features. The cushion is coupled to a shell,not shown. One unique feature of this embodiment is that by strategicplacement of pleats 290 and 292, this cushion provides a hinge-likeaction. With reference to FIG. 11, pleats 290 and 292 form a pair ofintegral hinges generally opposed to one another. Pleat 292 allows themiddle apex region 264 and middle side regions 266 to flex easier thanmiddle bottom region 268. Often with such cushions a conduit may extendoutward at a variety of different angles. The second pleat permits thecushion to easily adapt as the angle between the cushion and conduitchanges. Pleat 290 allows middle side regions 266 and middle bottomregion 268 to flex together easier than middle apex region 264. Pleat290 acts in a similar manner as pleat 82 in the previous embodimentwhich is more responsive to forces applied to the flap portion.

Cushion 232 may be formed with any of a variety of methods commonlyknown in the art. Preferably, cushion 232 is formed by an injectionmolding process. The pleats provide an integral secondary flap withoutthe need to form an undercut as is necessary in cushions which utilizean internal secondary flap. Cushion 232 may be formed from any suitablematerial. Preferably, the cushion is manufactured from an elasticmaterial such as silicone. Of course, a variety of other materials maybe utilized without departing from the present invention.

Another embodiment of the invention is shown in FIGS. 12-16 in which theunique aspects of the present invention are incorporated into a nasalpillow 300. An exemplary nasal pillow is fully disclosed in U.S. patentapplication Ser. No. 10/918,832, the contents of which are herebyincorporated by reference herein. The nasal pillow 300 of the presentinvention includes nare elements 302 terminating at an opening 304. Nareelements 302 are joined together by outlet legs 306 that merge togetherinto body 308. Body 308 has an inner curved surface 310 and an outercurved surface 312 defining an internal cavity 313 therebetween. Body308 terminates at an opening 314.

As best appreciated with reference to FIGS. 13 and 14, the body alsoincludes alignment rails 316, alignment fin 318, and bosses or mountingtabs 320. With reference to FIGS. 17 and 18, the cushion is connected tocoupling 322. The coupling has a rear exhaust plate 324 and slots 326.Alignment rails 316 fit into slots 326 to interconnect cushion 300 withcoupling 322. The pillow 300 is supported by a deformable support 330.Deformable support 330 includes a stem portion 332 and cross portion334. The stem portion has a slot 340, and the cross portion 334terminates at ends 336 having holes 338 therethrough. Deformable support330 is connected to pillow 300 by passing each boss 320 through acorresponding one of the holes 338. In addition, alignment fin is passedthrough slot 340.

One unique aspect of this embodiment is that each nare element 302includes at least one pleat 342 that extends around a portion of eachnare element 302. As in the prior embodiments, the pleats permit thenare elements 302 to articulate in a controlled manner. For instance,the pleats may be oriented with the region of deepest recess alignedwhere the most flexibility is desired. As best appreciated withreference to FIG. 16, each nare element has an approximately ellipticalcross-section defining a major axis 344 and a minor axis 346 orthogonalto the major axis. Of course, the shape of the nares may have a varietyof other shapes without departing from the scope of the presentinvention. The pleats, in FIG. 16, are oriented such that the regionwith the deepest recess is approximately aligned with the major axis 344of each nare element 302 and gradually become shallower towards theminor axis 346. This configuration permits the nare elements 302 to bemore flexible and thus pivot along the major axis while simultaneouslybeing relatively more rigid and resist bending along the minor axis 346.

With reference to FIG. 19, the nare elements may be further enhanced byforming pleats 342 with a thinner wall thickness in the region ofdeepest recess. This further permits the nare elements to pivot as wellas rotate. The nares may pivot along the major axis and/or rotate abouttheir center in a controlled manner to accommodate the particular nasalconfiguration of different users. Of course, the pleats may be placed inother locations about the nare elements to promote localized pivoting asdeemed desirable without departing from the teachings of the presentinvention.

One advantageous aspect of this invention is that its unique aspects maybe localized in particular regions where their unique characteristicsare desirable rather than extending completely about the cushion orpillow. Although the figures disclose a particular configuration, one ofordinary skill in the art can best appreciate that the pleats and wallthickness may be modified to address particular issues in various maskconfigurations such as full face masks, nasal masks, nasal-oral masks,or nasal pillows. In the event that a particular region is too rigid inthe axial direction, the wall thickness could be varied, the depth ofthe flap could be varied, and/or a pleat could be added. In the eventthat a particular region, experiences increased radial forces, the wallthickness could be increased, the length of the flaps could bedecreased, and/or pleats could be added.

Although the invention has been described in detail for the purpose ofillustration based on what is currently considered to be the mostpractical and preferred embodiments, it is to be understood that suchdetail is solely for that purpose and that the invention is not limitedto the disclosed embodiments, but, on the contrary, is intended to covermodifications and equivalent arrangements that are within the spirit andscope of the appended claims. In addition, specific features of thisinvention are shown in some drawings and not others, this is forconvenience only as each feature may be combined with any or all of theother features in accordance with the invention. Other embodiments willoccur to those skilled in the art and are within the following claims:

1. A cushion for use in a respiratory mask, the cushion comprises: aflap portion; a middle portion adjacent the flap portion; a connectionportion adjacent the middle portion; and a pleat formed about a portionof the cushion, wherein the cushion has an apex region, a pair of sideregions extending from the apex region, and a bottom regioninterconnected between the pair of side regions, wherein the pleatextends continuously about the bottom region and at least a portion ofthe side regions.
 2. The cushion as recited in claim 1, wherein the flapportion comprises: an apex flap having a length; a pair of side flapshaving a length; and a bottom flap having a length.
 3. The cushion asrecited in claim 2, wherein the length of the apex flap is longer thanthe length of the bottom flap.
 4. The cushion as recited in claim 1,wherein the flap portion has a thickness, the middle portion has athickness, the connection portion has a thickness, and wherein thethickness of the flap portion is less than the thickness of theconnection portion.
 5. The cushion as recited in claim 1, wherein thepleat is adjacent the flap portion.
 6. The cushion as recited in claim1, wherein the pleat is adjacent the connection portion.
 7. The cushionas recited in claim 1, wherein the cross-sectional depth of the pleatvaries.
 8. A respiratory mask for use in delivering a gas to a userthrough a conduit, the respiratory mask comprising: a shell, the shellhaving a coupling connected to the conduit; and a cushion coupled to theshell, the cushion comprising: a flap portion; a middle portion adjacentthe flap portion; a connection portion adjacent the middle portion; anda pleat formed about a portion of the cushion proximate the flapportion, wherein the cushion has an apex region, a pair of side regionsextending from the apex region, and a bottom region interconnectedbetween the pair of side regions, wherein the pleat extends continuouslyabout the bottom region and at least a portion of the side regions. 9.The cushion as recited in claim 8, wherein the flap portion comprises:an apex flap having a length; a pair of side flaps having a length; anda bottom flap having a length.
 10. The cushion as recited in claim 9,wherein the length of the apex flap is longer than the length of thebottom flap.
 11. The cushion as recited in claim 8, wherein the flapportion has a thickness, the middle portion has a thickness, theconnection portion has a thickness, and wherein the thickness of theflap portion is less than the thickness of the connection portion. 12.The cushion as recited in claim 8, wherein the pleat is adjacent theflap portion.
 13. The cushion as recited in claim 8, wherein the pleatis adjacent the connection portion.
 14. The cushion as recited in claim8, wherein the cross-sectional depth of the pleat varies.
 15. A cushionfor use in a respiratory mask, the cushion comprises: a flap portion; amiddle portion adjacent the flap portion; a connection portion adjacentthe middle portion; and means for providing a spring-type region about aportion of the cushion responsive to forces applied to the cushion,wherein the cushion has an apex region, a pair of side regions extendingfrom the apex region, and a bottom region interconnected between thepair of side regions, wherein the means extends continuously about thebottom region and up at least a portion of the side regions.
 16. Thecushion as recited in claim 15, wherein the flap portion comprises: anapex flap having a length; a pair of side flaps having a length; and abottom flap having a length.
 17. The cushion as recited in claim 15,wherein the length of the apex flap is longer than the length of thebottom flap.
 18. The cushion as recited in claim 15, wherein the flapportion has a thickness, the middle portion has a thickness, theconnection portion has a thickness, and wherein the thickness of theflap portion is less than the thickness of the connection portion. 19.The cushion as recited in claim 15, wherein the pleat is adjacent theflap portion.
 20. The cushion as recited in claim 15, wherein the pleatis adjacent the connection portion.